Safety release apparatus

ABSTRACT

Apparatus for releasing a rope from a pulley upon sensing the proximity of an object attached to the rope, particularly adapted for use with a ski rope tow apparatus for stopping the rope tow when a skier approaches too close to the rope tow return pulley.

14 1 May 7,1974

[54] SAEETY RELEASE APPARATUS 2,608,935 9/1952 Moore et a1. 104/173 [76] Inventor: John W. Elsing, 7202 Shannon Dr.,

Edina, Minn. 55435 Primary Examiner-Richard E. Aegerter [22] Filed Dec 26 1972 Assistant Examiner-Jeffrey V. Nase Attorney, Agent, or FirmPaul L. Sjoquist [21] Appl. No.1 318,531

52 us. 01. 254/173 R, 74/2426, 104/173 ST [571 ABSTRACT 51 Int. Cl B66d H48 [58] Field of Search 254/172, 173, 174;

Apparatus for releasing a rope from a pulley upon sensing the proximity of an object attached to the rope, particularly adapted for use with a ski rope tow apparatus for stopping therope tow when a skier ap- [56] References Cited proaches too close to the rope tow return pulley.

UNITED STATES PATENTS 3,209,703 10/1965 Brebner 104/173 11 Claims, 4 Drawing Figures ll/III/IIIII/(IltZ/III/Il/IIIIIIIIIII/fl T I SAFETY RELEASE APPARATUS This invention relates to a ski rope tow mechanism; more particularly, the invention relates to a safety device for use with a ski rope towing mechanism or other apparatus having a moving rope driven over a rotating pulley. The invention causes the rope to disengage from the pulley in the event a skier or other object comes into proximity of the pulley, such as could occur if a skier using the rope tow became entangled in the rope.

The principal object of the invention is to prevent a person from becoming entangled between the rope and the pulley, thereby preventing the possibility of physical injury to the person.

Another object of this invention is to provide a positive, direct-actuating safety release device to immediately disengage a rope from its drive mechanism when a skier or other object comes within a minimum safe distance of the rope pulley.

A further object of this invention is to provide a pulley and safety mechanism which is light in weight and portable for simple assembly of a ski rope tow which is safe in operation.

The sport of downhill skiing has been enhanced by various types of mechanized apparatus for towing or lifting a skier from the bottom of a hill back to the top. The simplest of these mechanized devices has generally included an endless rope driven at a first location by a motor apparatus, andsecured at a second location by a rotatable return pulley apparatus. The motor driving apparatus may be located either at the bottom or the top of a hill, with the secured return pulley apparatus located at the respective other position.

It is necessary to provide some sort of safety precaution about the pulley apparatus to prevent skiers from coming into contact with the rotating pulley, or from becoming entangled between the rope and pulley. These safety precautions have taken the form of guards around the pulley apparatus, electric switching devices coupled to the drive motor apparatus for shutting off the drive motor when the switching device is tripped, or other similar devices.

The present invention is primarily adaptable to a motor and drive pulley system located at the top of a hill, where it provides a direct-actuating, positive device for slipping the tow rope over and off the drive pulley, thereby releasing the mechanized drive force from the rope when a skier approaches too close to the pulley. The invention is useful, for example, when a skier who is towed to the top of the hill either fails to release his grip on the rope as he approaches the drive pulley, or becomes entangled in the rope; The invention assures the rope drive disengagement before the skier can come into contact with the pulley.

Because this inventive safety release mechanism is of simple mechanical construction it is adaptable to use in portable rope tow arrangements whereby the motor drive can be quickly set up at the top of a hill and the return pulley can be secured at the bottom of the hill and a tow rope connected between them. No other connections are needed to insure completely safe operation of the ski tow apparatus, since the inventive safety release mechanism may be made an integral part of the motor drive system.

The operation and advantages of the invention will become further apparent from a reading of the following specification and claims, together with the accompanying drawings, wherein like parts are referred to and indicated by like reference characters, and wherein:

FIG. 1 is a side view showing the invention and drive pulley apparatus;

FIG. 2 is a top view of the invention and pulley apparatus;

FIG. 3 is a side view showing the invention after the safety release feature has been activated;

FIG. 4 shows the operation of the invention near the end of one revolution of drive pulley rotation.

Referring first to FIG. 1, a drive pulley 10 is shown having a tow rope 11 riding in the pulley channel. The two rope 11 is an endless rope, being looped around a return pulley mechanism at a remote location (not shown) whereby the rope is driven in a'direction indicated by arrow 12. Drive pulley 10 and its associated apparatus, including the inventive safety release mechanism, is preferably anchored near the top of aski hill, and the return pulley apparatus is anchored near the bottom of the hill.

Drive pulley 10 is mounted on shaft 14, which in turn is connected to a suitable motor driving system (not shown). The entire apparatus is attached to mounting base 15, which is secured to the ground. Also mounted on shaft 14 is bearing 18, which bearing rolls freely as the shaft rotates. Attached to bearing 18 is rope deflector bar 20 which is freely rotatable about shaft 14 by means of bearing 18. Rope deflector bar 20 is held in the position shown in FIG. 1 by means of projection 19 on tip rod 21. Projection 19 protrudes through slot 22 in rope deflector bar 20 and holds the rope deflector bar in approximately the position shown. Trip rod 21 is attached to mounting plate 23 by means of loops 24. Trip rod 21 is slideably held within loops 24 so that lateral movement, either left or right, is possible. The end of trip rod 21 is formed in the shape of loop 25, or other convenient shape, so as to be actuated by a skier grasping the rope 11.

A spring-biased pawl 26 exerts a cross-axis force against trip rod 21, which somewhat restricts the freedom of lateral movement of trip rod 21. Pawl 26 rests in a shallow detent in trip rod 21 when trip rod 21 is in the position shown in FIG. 1; the cross-axis force is sufficient to resist any lateral movement of trip .rod 21 caused by frictional forces resulting from rope ll rubbing against loop 25 in normal operation.

When a skier who is grasping rope 11 comes into contact with loop 25, trip rod 21 is forced to slide laterally to the left, overcoming the relatively small crossaxis force of pawl 26. This lateral movement causes projection 19 at the opposite end of trip rod 21 to slide along slot 22. Because rope deflector 20 is bent in an S-shape, as can best be seen in FIG. 2, projection 19 slides to a position in slot 22 where projection 19 no longer protrudes through the slot. When this position is reached, rope deflector bar 20 becomes free to rotate about shaft 14 on its bearing 18. Bearing drag, and the force of gravity, cause rope deflector bar 20 to drop downward into a position between rope 11 and pulley 10. Once this occurs the operation proceeds as illustrated in FIG. 3 and FIG. 4, as hereinafter described.

FIG. 2 also shows the means by which shaft 14 is attached to mounting base 15. Shaft 14 is attached by means of bushing or bearing 28. The other end of shaft 14 (not shown) is attached to a suitable mounting base by means of a similar bushing or bearing, and a suitable motor driving source may be coupled to shaft 14 at any convenient point along its length. 1

FIG. 3 illustrates rope deflector bar 20 at a point in its downward rotational travel where it has begun to disengage rope 11 from drive pulley 10. In this position rope 11 is forced out of the channel of drive pulley at approximately point 29. Because rope deflector bar 20 is wedged between rope 11 and drive pulley 10, it will continue its rotationalmovement around shaft 14.

FIG. 4 illustrates the position of rope deflector bar 20 near the end of its travel about shaft 14. In the position shown rope 11 is nearly completely disengaged from the channel of drive pulley 10. Complete disengagement causes rope 11 to fall and to ride upon shaft 14. Shaft 14 continues to rotate but does not have enough frictional force to drive rope 11, and the movement of rope 11 therefore immediately stops.

It should be emphasized that with this invention the ski rope tow is stopped within one rotation of the rope deflector bar 20. This corresponds to a rope distance equal to approximately three-fourths the circumference of pulley 10. For example, assuming a drive pulley diameter of eight inches, the invention stops the ski rope tow movement in a linear travel distance of about eighteen inches. Using these parameters, trip rod 21 must have the freedom and capability of a lateral movement slightly greater than eighteen inches, the stopping distance.

Once the invention has been actuated to release the ski tow rope from pulley 10 it may be reset for further operation by merely latching the projection 19 of trip rod 21 back into slot 22 of rope deflector bar 20. The

ski tow rope may then be returned from shaft 14 to the channel of drive pulley 10 for continuing operation of the ski tow.

Other variations and embodimens may be used to practice this invention. For example, the bend in the rope deflector bar may be shaped differently from that shown in the figures, the rope deflector bar may be located on the opposite side of pulley 10 from that shown, and the functions performed by slot 22 and projection 19 may be accomplished by other structures. The shape of loop 25 may be varied and diverse, either completely or partially enclosing rope l1, and the means for slideably attaching trip rod 21 may be modified within the spirit of the invention. Other selections of shape, size and form may be adopted in the practice of this invention, the scope of which is to be limited solely by the-claims;

What is claimed is:

1. Apparatus for releasing a rope from moving about a pulley attached to a rotating shaft mounted on a base, comprising a bearing on said shaft positioned alongside said pulley; a bar having an S-bend and connected at one of its ends to said bearing, said S-bend extending the free end of said bar across the width of said pulley,

said bar also having an elongated slot near its free end and extending along its length at least partially through the region of said S-bend; a trip rod slideably affixed on said base relative to said bar elongated slot, said trip rod having a projection at its first end for insertion into vsaid elongated slot, and a projection at its second end extending near said rope for reacting to objects attached to said moving rope; whereby an object attached to said moving rope causes said second end projection to react and slideably disengage said first end projection from said slot allowing said bar free end to fall downwardly between said moving rope and pulley and rotate therewith to separate said rope from said pulley.

2. Apparatus as claimed in claim 1, wherein said trip rod projection at its second end comprises a loop encircling said rope.

3. Apparatus as claimed in claim 2 wherein said trip rod is of a length and slideably affixed in a manner to allow said trip rod to slide a distance greater than the mean circumference of said pulley.

4. Apparatus as claimed in claim 3, further comprising a spring-biased pawl mounted on said base and urged against said trip rod for resisting sliding movement of said trip rod caused by frictional forces of said rope.

5. A safety release mechanism for releasing a moving rope from a rotating pulley attached to a shaft comprismg:

a. a mounting base having shaft bearings for securing said shaft, and having means for attaching thereto a motor driving apparatus;

b. a release bar rotationally mounted to said shaft by means of a bearing, said bearing positioned adjacent said pulley and said release bar having an S- bend near its free end extending said free end across the width of said pulley;

c. aslot in saidrelease bar extending from a region near said free end to a region in said S-bend;

. a trip rod slideably mounted on said base said trip rod having a projection near its first end for sliding engagement with said slot;

e. an actuating arm attached to the second end of said trip rod and positioned near said moving rope, said actuating arm responsive to contact of objects attached to said moving rope to cause said trip rod first end projection to slide in said release bar slot to said S-bend region and to thereby disengage from said slot and allow said release bar free end to drop into interposition between said moving rope and said rotating pulley and to rotate therewith and cause said rope to release from contact with said pulley.

6. Apparatus as claimed in claim 5, wherein said S- bend begins at a point along said bar a distance from said shaft greater than the radius of said pulley.

7. Apparatus as claimed in claim 6, wherein said trip rod projection engages said slot for only a portion of said slot length.

8. Apparatus as claimed in claim 7, wherein said slot length extends at least into the region of curvature of said S-bend in said release bar.

9. Apparatus as claimed in claim 8, wherein said actuating arm encircles said rope.

10. Apparatus as claimed in claim 9, wherein said trip rod sliding distance is approximately equal to the circumference of said pulley.

11. Apparatus as claimed in claim 10, further comprising a spring-biased pawl attached to said base, said pawl urged against said trip rod to resist lateral movement of said trip rod. 

1. Apparatus for releasing a rope from moving about a pulley attached to a rotating shaft mounted on a base, comprising a bearing on said shaft positioned alongside said pulley; a bar having an S-bend and connected at one of its ends to said bearing, said S-bend extending the free end of said bar across the width of said pulley, said bar also having an elongated slot near its free end and extending along its length at least partially through the region of said S-bend; a trip rod slideably affixed on said base relative to said bar elongated slot, said trip rod having a projection at its first end for insertion into said elongated slot, and a projection at its second end extending near said rope for reacting to objects attached to said moving rope; whereby an object attached to said moving rope causes said second end projection to react and slideably disengage said first end projection from said slot allowing said bar free end to fall downwardly between said moving rope and pulley and rotate therewith to separate said rope from said pulley.
 2. Apparatus as claimed in claim 1, wherein said trip rod projection at its second end comprises a loop encircling said rope.
 3. Apparatus as claimed in claim 2 wherein said trip rod is of a length and slideably affixed in a manner to allow said trip rod to slide a distance greater than the mean circumference of said pulley.
 4. Apparatus as claimed in claim 3, further comprising a spring-biased pawl mounted on said base and urged against said trip rod for resisting sliding movement of said trip rod caused by frictional forces of said rope.
 5. A safety release mechanism for releasing a moving rope from a rotating pulley attached to a shaft comprising: a. a mounting base having shaft bearings for securing said shaft, and having means for attaching thereto a motor driving apparatus; b. a release bar rotationally mounted to said shaft by means of a bearing, said bearing positioned adjacent said pulley and said release bar having an S-bend near its free end extending said free end across the width of said pulley; c. a slot in said release bar extending from a region near said free end to a region in said S-bend; d. a trip rod slideably mounted on said base said trip rod having a projection near its first end for sliding engagement with said slot; e. an actuating arm attached to the second end of said trip rod and positioned near said moving rope, said actuating arm responsive to contact of objects attached to said moving rope to cause said trip rod first end projection to slide in said release bar slot to said S-bend region and to thereby disengage from said slot and allow said release bar free end to drop into interposition between said moving rope and said rotating pulley and to rotate therewith and cause said rope to release from contact with said pulley.
 6. Apparatus as claimed in claim 5, wherein said S-bend begins at a point along said bar a distance from said shaft greater than the radius of said pulley.
 7. Apparatus as claimed in claim 6, wherein said trip rod projection engages said slot for only a portion of said slot length.
 8. Apparatus as claimed in claim 7, wherein said slot length extends at least into the region of curvature of said S-bend in said release bar.
 9. Apparatus as claimed in claim 8, wherein said actuating arm encircles said rope.
 10. Apparatus as claimed in claim 9, wherein said trip rod sliding distance is approximately equal to the circumference of said pulley.
 11. Apparatus as claimed in claim 10, further comprising a spring-biased pawl attached to said base, said pawl urged against said trip rod to resist lateral movement of said trip rod. 